Ball-caster.



N0. 636,757. Patented Nov. I4, |899. E. P. -H. CARRAWAY.

BALL EASTER.

UNITED STATES PATENT OFFICE.

ESTHER P. H. OARRAWAY, OF PORTSMOUTH, VIRGINIA, ASSIGNOR OF ONE- HALF TO FRANK N. BILISOLY, OF SAME PLACE, AND ALEXANDER S. HUDSON, OF CHAPEL HILL, TEXAS.

BALL-CASTER.

SPECIFICATION forming part of Letters Patent No. 636,757, dated November 14, 1899.

Application filed June 3,1899. Serial No. 719,262. (No model.)

To all whom, it may concern:

Be it known that I, ESTHER P. H. CARRA- WAY, a citizen of the United States, residing at Portsmouth, in the county of Norfolk and State of Virginia, have invented a new and useful Ball-Caster, of which the following is a specicaion.

This invention relates to ball-casters, and has for its object to provide certain new and 1o useful improvements in the structure of the mounting of the ball, which permit the ready assembling of the parts.

To this end the present invention consists in the combination and arrangement of parts I5 as will be hereinafter more fully described, shown in the accompanying drawings,and particularly pointed out in the appended claim, it being understood that changes in the form, proportion, size, and the minor details of conzo struction may be made within the scope of the appended claim without departing from the spirit or sacrificing any of the advantages of the present invention.

In the drawings, Figure 1 is an elevation of 2 5 a caster, showing the same fitted to the leg of a piece of furniture. Fig. 2 is a longitudinal sectional view thereof. Fig. 3 is abottom plan view having the ball-retaining cap or ring removed.

3o Corresponding parts in the several figures of the drawings are designated by like characters of reference.

Referring to the accompanying drawings, 1 designates the body of the caster, which is substantially hemispherical and is provided with a socket or recess 2, opening outward through the iiattened side of the caster-body. Located at the opposite side of the body and projecting exteriorly therefrom is theusual 4o attaching-shank 3, which is adapted to be fitted to the leg 4 of a piece of furniture in the common or ordinary manner.

As best shown in Fig. 2 of the drawings,it will be seen that the socket 2 is widened near the mouth thereof, whereby an inner annular shoulder 5 is provided and also a pendent peripheral flange 6. Located within the socket 2 is the ball 7, which is provided with a horizontal axial bore 8, the diameter of which is 5o smallest at a point midway between the opposite ends of the bore, and the latter uniformly increases in size from the center outwardly and in opposite directions therefrom. Mounted loosely within the bore of the ball is a shaft 9 which projects equally beyond 55 the opposite ends of said bore and has a bearing upon the ball only at the intermediate point 10, where the diameter of the bore is smallest. The opposite projecting ends 11 of the shaft 9 provide journals upon which are 6o loosely mounted the disk rollers or wheels 12, which are received in the groove formed between thc annular shoulder 5 and the peripheral flange 6, so that said rollers are adapted to engage with and travel upon the annular shoulder 5. In order that these movable parts of the caster may be held in position., there is provided a retaining-ring 13, which has an upstanding peripheral flange 14, threaded ex teriorly and adapted to be fitted to the inte`v 7o riorly threaded portion of the peripheral flange 6. This retaining ring or cap has an opening 15, through which the lower side of the ball is adapted to project and rest upon the floor, and the upper side of the ring is also provided with an inner annular groove 16, adapted to receive the lower side of the rollers 12. It will be noted that the groove 17 in the body of the caster and also the groove 16 in the retaining-ring are adapted to 8o register, so as to form a large annular groove receiving and confining the rollers 12, and also the sides of the ball, at the opposite ends of the bore therein, are flattened, as at 18, so as to accommodate the adjacent iiat sides of the disk rollers, and thereby prevent the latter` from having a wabbling or lateral movement upon the journals 11 or ends of the shaft 9. By reason of the oppositely-tapered shape of the bore of the ball the latter has a bear 9oing at a single point only intermediate of the ends of the shaft, whereby friction is reduced to a minimum, and should the ball be canted A or tilted the graduallyiincreasing size of the bore will prevent the same from binding upon the shaft, thereby insuring a positive and easy turning of the ball. The annular shoul der 5 of the body of the caster rests upon the periphery of the rollers 12 at the upper sides thereof, and the shaft 9 is supported inter roo mediate of its ends upon the lower wall and at the narrowest portion of the bore S, whereby the ball is capable of turning upon its vertical axis, and the rollers l2 turning loosely upon the ends of the shaft and traveling against the comparatively small surface presented by the annular shoulder 5 the friction caused by such movement is also reduced to a minimum.

It will be noted that the ball 7 does not engage the walls of the socket 2; but the body of the caster is supported at opposite points upon the rollers 12 and the shaft 9 engages the ball at only one point, whereby the frictional surfaces are greatly reduced and a substantially' three-point bearing is provided.

To facilitate the positioning and removal 'of the retaining cap or ring 13, the latter is 'roughened or serrated cxteriorly,as indicated securing-stem integral therewith and having a substantially hem ispherical recess in its under side, a groove in the wall of the lower portion of the recess resulting in the formation of a lower increased cylindrical bore, and a race element between the wall of the cylindrical bore and the wall of the hemispherical recess, threads at the lower end of the body portion, a retaining-ring engaging the threads of the body portion and having a groove in the upper portion of its inner -surface resulting in the formation of an increased cylindrical bore adapted to aline with the similar portion of the body, and a race element adapted to lie parallel with the race element of the body to form a race, rollers mounted to travel in the race, a shaft journaled loosely in the rollers and movable therewith, and a ball having a central passage, the ends of which are flared outwardly and through which the shaft is passed, the surface of the ball surrounding the ends of the passage being adapted to contact with the rollers to hold the ball from engagement with the body and the ring.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence of two witnesses.

ESTHER I. II. CARRAXVAY. lVitnesses:

J. BYRON WHITEHURST, K. J. GRIFFIN. 

